Method of manufacturing coffee extract allowing long-term preservation

ABSTRACT

It is the object of the present invention to provide a coffee extract manufacturing method which prevents deterioration of flavor and precipitation in the coffee extract during long-term preservation and also keeps a sealed container filled with the coffee extract from expanding to deform or break for long preservation or heat sterilization. The invention is directed to a coffee extract manufacturing method allowing a long-term preservation, which has achieved the above object by adding strong alkaline salt that is alkaline noncarbonate into coffee extract.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a method of manufacturing acoffee extract allowing a long-term preservation, and more particularlyto a coffee extract manufacturing method, allowing a long-termpreservation of a coffee extract that has a high concentration of solidcontent and is diluted for drinking.

2. Description of the Related Art

Some components in coffee extract become insoluble and precipitateduring long-term preservation. The amount of precipitation is especiallylarge in coffee extract which has high concentration of solids contentand is diluted for drinking, and this reduces the value of the product.This precipitation occurs even during refrigeration, and accelerates inordinary temperature.

The precipitation of insoluble components in coffee extract proceedsfrom the decline of hydrogen ion exponent (pH), which causes not onlyprecipitation or cloudiness in coffee extract but also deterioration offlavor accompanied with increase of sourness.

Therefore as a method of preventing this precipitation and deteriorationof flavor, there has been proposed a manufacturing process containingaddition of sodium hydrogen carbonate into coffee extract(JapanesePatent Laid-open Pub. Nos. 61-74543, 2-222647, 6-2925).

However, if coffee extract is filled into a sealed container, the use ofa large quantity of alkaline carbonate, such as sodium hydrogencarbonate mentioned above, causes gas because of long preservation orheat sterilization with the result that the container expands to deformand break. The invention purposes to solve these problems and hasachieved its purpose by the completion of the invention mentioned below.

SUMMARY OF THE INVENTION

The invention prevents the decline of hydrogen ion exponent of coffeeextract resulted from long-term preservation and uses alkalinenoncarbonate which does not produce gas causing expansion of acontainer. Adding alkaline noncarbonate into coffee extract preventsprecipitation or deterioration of flavor resulting from longpreservation, and if the coffee extract is filled into a sealedcontainer, it also prevents occurrence of gas resulting from passage oftime or heat sterilization which causes expansion, deformation, andbreakage of the container.

This invention makes it possible to make a long-term preservation ofcoffee extract by adding strong alkaline salt that is alkalinenoncarbonate to modulate hydrogen ion concentration in the coffeeextract. The modulation of hydrogen ion concentration is to make itsuitable to avoid precipitation in the coffee extract during long-termpreservation, and its condition depends on soluble solids concentration(Bx) of the coffee extract. The hydrogen ion exponent(pH) in the coffeeextract after sterilization and aseptic filling into a sealed containershould be modulated to be 5.3 or above, and more preferably, 5.6 orabove. This process makes it possible to prevent the decline of pH,which causes cloudiness precipitation, or deterioration of flavor incoffee extract during long-term preservation.

Either or both of sodium hydroxide and potassium hydroxide can be usedas strong alkaline salt.

The invention also makes it possible to make a long-term preservation ofcoffee extract by replacing a part of strong alkaline salt with alkalinecarbonate to modulate hydrogen ion concentration of the coffee extract.As alkaline carbonate to replace, sodium carbonate or sodium hydrogencarbonate (sodium bicarbonate) can be added, and its amount to adddepends on the rate of the volume of the container and coffee extract orthe length of preservation. For example, when coffee extract is filledto 80% by volume of the container and the rest 20% is empty, the amountof alkaline carbonate to add should be less than 0.5% by weight of theextract, and more preferably, less than 0.3% by weight.

This invention also makes it possible to make a long-term preservationof coffee extract by adding acid to remove precipitation beforemodulating hydrogen ion concentration of the coffee extract, and then,adding only strong alkaline salt or both strong alkaline salt andalkaline carbonate to modulate hydrogen ion concentration of the coffeeextract.

Acid added before modulation of hydrogen ion concentration is carriedfor the purpose of removing the precipitation resulted from decline ofpH in the coffee extract as much as possible beforehand, and it dependson soluble solids concentration as well as the modulation of hydrogenion concentration mentioned above. Hydrogen ion exponent (pH) of thecoffee extract filled into a container should be lowered by 0.05 atleast, and preferably, by more than 0.1. This process can reduce theamount of precipitation that occurs during long preservation, andprevent decline of hydrogen ion exponent resulted from passage of timewhich brings deterioration of flavor and precipitation. This is becauseadding strong alkali to weak acid makes an environment which servesbuffer action and the decline of pH in the coffee extract is restrainedmore effectively than the case of adding only strong alkali, with theresult that precipitation becomes less likely occur.

As acid added before modulation of hydrogen ion concentration, not onlyorganic acid such as citric acid, malic acid, or L-Ascorbic acid, butalso inorganic acid such as phosphoric acid or hydrochloric acid, can beused alone or combined, but using organic acid is more preferable, whenthe flavor of coffee extract as a beverage product is emphasized.

Embodiment of the Invention

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described.

Coffee extract is can be obtained by extracting from roasted coffeebeans with a desired method such as using cold, warm, or hot water. Inthis invention the method of extracting does not have to be limited andany method can be adopted. Therefore the following examples used coffeeextract produced with hot water from roasted coffee beans.

First, in Experiment 1, to present comparable objects to judge theeffect of the invention, following points: 1 flavor 2 deformation ofcontainer 3 precipitation: were evaluated about several kinds of coffeeextract varying in the amount of sodium hydrogen carbonate added withthe method of the prior art in order to preserve it for long. Theevaluation above was done on both the one immediately aftersterilization for preserving and the one after preservation.

Coffee extract to be evaluated was prepared through process of addingsodium hydrogen carbonate into coffee extract produced from roastedcoffee beans with hot water, modulating soluble solids concentration(Bx) to be 15 degrees, sterilizing for 30 seconds at 135° C., fillingaseptically 4000 g each into a 51-1 BIB (Bag-In-Box) container composedof a plastic bag and a paper box, and preserving it for 30 days at 25°C. Coffee extract containing no sodium hydrogen carbonate was alsoprepared together.

In the evaluation of 1 flavor, preserved coffee extract was diluted sothat the soluble solids concentration is 1.5 degrees and evaluated on ascale of 5 points in which 5 is the highest point. In the evaluation of2 deformation of container, appearance of the container filled with thepreserved coffee extract was observed, and evaluated with the followingmarks: ⊚no expansion of the inner bag recognized, ∘expansion of theinner bag recognized but no deformation of the outer box, xdeformationof the outer box recognized. In the evaluation of 3 precipitation, 10 mlof the preserved coffee extract was put into a centrifugal tube andcentrifuged for 10 minutes at 3000 rpm, and then evaluated with thefollowing marks: ⊚no precipitation occurred, Δslight cloudinessoccurred, xprecipitation occurred. Table 1 below shows the result.

                  TABLE 1                                                         ______________________________________                                                    amount of addition (wt %)                                         sodium hydrogen carbonate                                                                   0.00    0.10    0.15  0.30  0.45                                ______________________________________                                        pH before sterilization                                                                     5.32    5.80    5.94  6.65  6.90                                pH right after sterilization                                                                4.97    5.38    5.52  5.80  5.89                                1 flavor      2       4       5     5     5                                   2 deformation of container                                                                  ⊚                                                                      ⊚                                                                      ⊚                                                                    ⊚                                                                    ⊚                    3 precipitation                                                                             x       Δ ∘                                                                       ∘                                                                       ∘                       pH 30 days later                                                                            4.76    4.88    5.06  5.34  5.48                                1 flavor      1       2       3     4     4                                   2 deformation of container                                                                  ⊚                                                                      ⊚                                                                      ∘                                                                       x     x                                   3 precipitation                                                                             x       x       x     Δ                                                                             ∘                       ______________________________________                                    

The result shown in Table 1 indicates that adding sodium hydrogencarbonate prevents precipitation and deterioration of flavor accompaniedby increase in sourness, while hydrogen ion exponent in normal coffeeextract greatly decreases by long-term preservation or heatsterilization. On the other hand, however, it is recognized that a largeamount of sodium hydrogen carbonate causes deformation of the containerin long-term preservation.

Then, in Embodiment 1, other alkaline salt in stead of sodium hydrogencarbonate was added into coffee extract, and after preserved, the coffeeextract was evaluated on the same points as in Experiment 1 mentionedabove. Coffee extract to be evaluated was prepared through process ofadding each alkaline salt to the coffee extract so that pH aftersterilization is almost the same as the one containing 0.45 wt % sodiumhydrogen carbonate of the extract, and then, in the same method ofExperiment 1, modulating soluble solids concentration to be 15 degrees,sterilizing for 30 seconds at 135° C., filling aseptically 4000 g of theextract into a 51-1 BIB container composed of a plastic bag and a paperbox, and preserving it for 30 days at 25° C. The result is shown inTable 2.

                  TABLE 2                                                         ______________________________________                                                    amount of addition (wt %)                                         ______________________________________                                        sodium hydrogen carbonate                                                                   0.45    --      --    --    --                                  sodium carbonate                                                                            --      0.28    --    --    --                                  sodium hydroxide                                                                            --      --      0.21  --    0.12                                potassium hydroxide                                                                         --      --      --    0.30  0.13                                pH after sterilization                                                                      5.89    5.84    5.79  5.76  5.80                                pH 30 days later                                                                            5.48    5.45    5.46  5.44  5.45                                1 flavor      4       4       4     4     4                                   2 deformation of container                                                                  x       x       ⊚                                                                    ⊚                                                                    ∘                       3 precipitation                                                                             ∘                                                                         ∘                                                                         ∘                                                                       ∘                                                                       ∘                       ______________________________________                                    

The result shown in Table 2 indicates that adding sodium carbonate,which is alkaline salt, prevents precipitation and deterioration offlavor as well as sodium hydrogen carbonate, while the containerseverely deformed and broke in this case. However, in case of addingsodium hydroxide or potassium hydroxide or both, which are strongalkaline salt, precipitation and deterioration of flavor were prevented,and moreover, there was less expansion of the bag and no influence onthe outer box. This result proved that the use of strong alkaline saltcan prevent precipitation and deterioration of flavor, and besides,solve the problem of deformation of a container.

Next, in Embodiment 2, a part of sodium hydroxide and potassiumhydroxide added into coffee extract, which are alkaline salt thatbrought preferable result in Embodiment 1 above, was replaced withsodium hydrogen carbonate, and this coffee extract was evaluated on thesame points as in Embodiment 1 with the amount of sodium hydroxide orpotassium hydroxide and sodium hydrogen carbonate varied. Each alkalinesalt and sodium hydrogen carbonate was added into the coffee extract sothat hydrogen ion exponent after sterilization is about the same as theone containing 0.45 wt % sodium hydrogen carbonate, as in Embodiment 1,and except for that, all conditions and method to prepare coffee extractwere the same as in Embodiment 1 above. Table 3 below shows the result.

                  TABLE 3                                                         ______________________________________                                                     amount of addition (wt %)                                        ______________________________________                                        sodium hydrogen carbonate                                                                    0.45   0.13   0.24 0.34 0.13 0.34                              sodium hydroxide                                                                             --     0.15   0.10 0.05 --   --                                potassium hydroxide                                                                          --     --     --   --   0.21 0.07                              pH after sterilization                                                                       5.89   5.77   5.81 5.78 5.79 5.80                              pH 30 days later                                                                             5.48   5.42   5.45 5.44 5.43 5.43                              1 flavor       4      4      4    4    4    4                                 2 deformation of container                                                                   x      ⊚                                                                     ∘                                                                      x    ⊚                                                                   x                                 3 precipitation                                                                              ∘                                                                        ∘                                                                        ∘                                                                      ∘                                                                      ∘                                                                      ∘                     ______________________________________                                    

The result shown in Table 3 indicates that in case of replacing a partof sodium hydroxide or potassium hydroxide with sodium hydrogencarbonate, precipitation and deterioration of flavor are prevented andthere is no influence on deformation of the container, as well as thecase of using sodium hydroxide or potassium hydroxide or both. On theother hand, in case of adding 0.34% sodium hydrogen carbonate into thecoffee extract, the container severely deformed and its outer box broke.According to this result, the desirable rate of strong alkaline saltsuch as sodium hydroxide or potassium hydroxide replaced with sodiumhydrogen carbonate is less than 0.34% by weight of coffee extract,preferably about 0.24% by weight, and more preferably about 0.13% byweight.

Next, in Embodiment 3, citric acid, which is organic acid, was addedinto coffee extract before modulating hydrogen ion concentration bystrong alkaline salt and then after removing precipitation in the coffeeextract, modulation of hydrogen ion concentration by strong alkalinesalt was done. This extract was evaluated on the same points as inEmbodiment 1 with the amount of citric acid to add varied. Coffeeextract to be evaluated was prepared through process of adding necessaryamount of citric acid into the coffee extract to lower hydrogen ionexponent by the required amount, leaving it for a while, removingprecipitation by centrifugation, adding sodium hydroxide to make pHafter sterilization 5.8, modulating soluble solids concentration to beabout 25 degrees, sterilizing for 30 seconds at 135° C., fillingaseptically 4000 g into a 51-1 BIB container, and then preserving it at25° C. for 30, 60, or 90 days. For Experiment 2, coffee extract intowhich no acid was added, was also prepared together. The result is shownin Table 4.

                  TABLE 4                                                         ______________________________________                                        pH decline by citric acid addition                                                                --     0.05   0.10 0.20                                   pH after addition of sodium hydroxide                                                             5.81   5.80   5.80 5.81                                   pH 30 days later    5.50   5.54   5.57 5.62                                   1 flavor            4      5      5    5                                      2 deformation of container                                                                        ⊚                                                                     ⊚                                                                     ⊚                                                                   ⊚                       3 precipitation     Δ                                                                              ∘                                                                        ∘                                                                      ∘                          pH 60 days later    5.23   5.32   5.38 5.49                                   1 flavor            3      4      5    5                                      2 deformation of container                                                                        ⊚                                                                     ⊚                                                                     ⊚                                                                   ⊚                       3 precipitation     x      Δ                                                                              ∘                                                                      ∘                          pH 90 days later    5.10   5.22   5.30 5.41                                   1 flavor            2      3      4    5                                      2 deformation of container                                                                        ⊚                                                                     ⊚                                                                     ⊚                                                                   ⊚                       3 precipitation     x      x      Δ                                                                            ∘                          ______________________________________                                    

The result shown in Table 4 indicates that adding citric acid beforemodulating hydrogen ion concentration by strong alkaline salt preventsdeterioration of flavor and deformation of container as well asprecipitation during preservation. However, because too small amount ofacid added to lower pH enough may not prevent precipitation resultingfrom long-term preservation, it is necessary to add enough amount ofacid to lower pH in coffee extract by about 0.05 in case of 30-daypreservation, by about 0.10 in case of 60-day preservation, and by about0.20 in case of 90-day preservation, for keeping the extract stable.

Next, in Embodiment 4, organic acid used in Embodiment 3 was changedfrom citric acid to L-Ascorbic acid, and the evaluation about the coffeeextract was done on the same points and in the same method to preparecoffee extract as in Embodiment 3. The result is shown in Table 5 below.

                  TABLE 5                                                         ______________________________________                                        pH decline by L-Ascorbic acid addition                                                            --     0.05   0.10 0.20                                   pH after addition of sodium hydroxide                                                             5.81   5.78   5.80 5.80                                   pH 30 days later    5.50   5.55   5.59 5.64                                   1 flavor            4      5      5    5                                      2 deformation of container                                                                        ⊚                                                                     ⊚                                                                     ⊚                                                                   ⊚                       3 precipitation     Δ                                                                              ∘                                                                        ∘                                                                      ∘                          pH 60 days later    5.23   5.34   5.39 5.48                                   1 flavor            3      4      5    5                                      2 deformation of container                                                                        ⊚                                                                     ⊚                                                                     ⊚                                                                   ⊚                       3 precipitation     x      Δ                                                                              ∘                                                                      ∘                          pH 90 days later    5.10   5.23   5.31 5.39                                   1 flavor            2      3      4    5                                      2 deformation of container                                                                        ⊚                                                                     ⊚                                                                     ⊚                                                                   ⊚                       3 precipitation     x      x      Δ                                                                            ∘                          ______________________________________                                    

The result shown in Table 5 indicates that the same level of effect oneach point of flavor, deformation of container, and precipitation isrecognized if organic acid added before modulation of hydrogen ionconcentration by strong alkaline salt is changed from citric acid toL-Ascorbic acid.

In addition, in Embodiment 5, citric acid that is organic acid was addedinto coffee extract before modulating hydrogen ion concentration in thecoffee extract by strong alkaline salt, and then after removingprecipitation, hydrogen ion concentration was modulated using bothstrong alkaline salt and sodium hydrogen carbonate. This coffee extractwas evaluated on the same points as in Embodiment 3 with the amount ofsodium hydrogen carbonate varied. Coffee extract to be evaluated wasprepared through process of adding citric acid into coffee extract tolower pH by about 0.4, leaving it for a while, removing precipitation bycentrifugation, adding required amount of sodium hydroxide to make pHafter sterilization 6.0, modulating soluble solids concentration to be20 degrees, sterilizing for 30 seconds at 135° C., filling 4000 gaseptically into a 51-1 BIB container, and preserving it at 25° C. for30, 60, or 90 days. For Experiment 3, coffee extract, in which no acidwas added, was also prepared together with the amount of sodium hydrogencarbonate to add varied. [Table 6] below shows the result.

                  TABLE 6                                                         ______________________________________                                        amount of addition of sodium                                                                 no citric acid added                                           hydrogen carbonate (wt %)                                                                    0.00    0.10    0.20  0.30 0.50                                ______________________________________                                        pH 30 days later                                                                             5.51    5.52    5.50  5.51 5.50                                1 flavor       4       4       4     4    4                                   2 deformation of container                                                                   ⊚                                                                      ∘                                                                         ∘                                                                       x    x                                   3 precipitation                                                                              Δ Δ Δ                                                                             Δ                                                                            Δ                             pH 60 days later                                                                             5.25    5.25    5.23  5.24 5.25                                1 flavor       3       3       3     3    3                                   2 deformation of container                                                                   ⊚                                                                      ∘                                                                         x     x    x                                   3 precipitation                                                                              x       x       x     x    x                                   pH 90 days later                                                                             5.14    5.14    5.13  5.14 5.14                                1 flavor       2       2       2     2    2                                   2 deformation of container                                                                   ⊚                                                                      ∘                                                                         x     x    x                                   3 precipitation                                                                              x       x       x     x    x                                   ______________________________________                                        amount of addition of sodium                                                                 citric acid added                                              hydrogen carbonate (wt %)                                                                    0.00    0.10    0.20  0.30 0.50                                ______________________________________                                        pH 30 days later                                                                             5.74    5.75    5.75  5.73 5.74                                1 flavor       5       5       5     5    5                                   2 deformation of container                                                                   ⊚                                                                      ⊚                                                                      ⊚                                                                    ∘                                                                      ∘                       3 precipitation                                                                              ∘                                                                         ∘                                                                         ∘                                                                       ∘                                                                      ∘                       pH 60 days later                                                                             5.60    5.60    5.59  5.58 5.60                                1 flavor       5       5       5     5    5                                   2 deformation of container                                                                   ⊚                                                                      ⊚                                                                      ∘                                                                       ∘                                                                      ⊚                    3 precipitation                                                                              ∘                                                                         ∘                                                                         ∘                                                                       ∘                                                                      ∘                       pH 90 days later                                                                             5.55    5.57    5.56  5.55 5.53                                1 flavor       4       4       4     4    4                                   2 deformation of container                                                                   ⊚                                                                      ⊚                                                                      ∘                                                                       ∘                                                                      x                                   3 precipitation                                                                              ∘                                                                         ∘                                                                         ∘                                                                       ∘                                                                      ∘                       ______________________________________                                    

The result shown in Table 6 indicates that deterioration of flavor,deformation of container and precipitation in coffee extract duringpreservation are avoided as well as in Embodiment 3, when citric acidthat is organic acid is added into the coffee extract before modulatinghydrogen ion concentration by strong alkaline salt and after removingprecipitation, hydrogen ion concentration is modulated by both strongalkaline salt and sodium hydrogen carbonate. Moreover, in case of adding0.34 wt % sodium hydrogen carbonate into coffee extract in Embodiment 2,even the container of 30-day preservation severely deformed and theouter box broke, while in case of adding citric acid to removeprecipitation in coffee extract, coffee extract added 0.30 wt % sodiumhydrogen carbonate could resist 90-day preservation, and the one added0.50 wt % sodium hydrogen carbonate could resist 60-day preservationthough soluble solids concentration (Bx) was higher than the case ofEmbodiment 2. This result proved that deformation of container isavoided if citric acid is added to remove precipitation beforemodulation of hydrogen ion concentration by strong alkaline salt, thoughmore sodium hydrogen carbonate is added together than the case of addingno citric acid.

Effect of the Invention

The above mentioned that the invention enabled long-term preservation ofcoffee extract by adding strong alkaline salt to prevent precipitationand deterioration of flavor. Moreover, with this method, a sealedcontainer filled with the coffee extract dose not expand to deform orbreak, because gas resulted from passage of time or heat sterilizationwill not occur as will do when alkaline salt carbonate is used.

Besides, the invention enables easier operation of modulating towarddesirable hydrogen ion concentration by using both strong alkaline saltand alkaline salt carbonate together, which realizes milder modulationof hydrogen ion concentration of coffee extract than using only strongalkaline salt.

In addition, the invention enabled long-term preservation of coffeeextract by adding acid before modulation of hydrogen ion concentrationby strong alkaline salt to prevent precipitation still more. Moreover,in the invention, addition of acid accompanied with alkali is possible,because this addition of acid is carried on the basis of the inventionthat modulation of hydrogen ion concentration is done by strong alkalineand therefore gas will not occur during the modulation, as will do ifacid is added on the basis of the prior method that modulation is doneby carbonate.

What is claimed is:
 1. A coffee extract manufacturing method comprisingthe step of adding a strong alkaline salt to a coffee extract tomodulate hydrogen ion concentration, in an amount to preventprecipitation or deterioration of the flavor resulting from longpreservation and, at the same time, when said extract is filled into asealed container, preventing occurrence of gas resulting from passage oftime or heat sterilization which can cause expansion, deformation andbreakage of the container.
 2. A coffee extract manufacturing methodaccording to claim 1, wherein strong alkaline salt added is either orboth of sodium hydroxide and potassium hydroxide.
 3. A coffee extractmanufacturing method according to claim 1, wherein a part of strongalkaline salt added is replaced with alkaline carbonate.
 4. A coffeeextract manufacturing method according to claim 1, wherein an acid isadded to create precipitate-forming conditions followed by removal ofprecipitates before modulating hydrogen ion concentration.
 5. A coffeeextract manufacturing method according to claim 2, wherein a part ofstrong alkaline salt added is replaced with alkaline carbonate.
 6. Acoffee extract manufacturing method according to claim 2, wherein anacid is added to create precipitate-forming conditions followed byremoval of precipitates before modulating hydrogen ion concentration. 7.A coffee extract manufacturing method according to claim 3, wherein anacid is added create precipitate-forming conditions followed by removalof precipitates before modulating hydrogen ion concentration.
 8. Acoffee extract manufacturing method to claim 5, wherein an acid is addedto create precipitate-forming conditions followed by removal ofprecipitates before modulating hydrogen ion concentration.
 9. A coffeeextract manufacturing method according to claim 1, comprising theadditional step of modulating the hydrogen ion concentration to pH 5.3or above.
 10. A coffee extract manufacturing method according to claim9, wherein the hydrogen ion concentration is modulated to pH 5.6 orabove.
 11. A coffee extract manufacturing method according to claim 3,wherein the alkaline carbonate is sodium carbonate or sodiumbicarbonate.
 12. A coffee extract manufacturing method according toclaim 11, wherein the amount of alkaline carbonate added is less thanabout 0.5% by weight of the extract.
 13. A coffee extract manufacturingmethod according to claim 12, wherein the amount of alkaline carbonateadded is less than about 0.3% by weight of the extract.
 14. A coffeeextract manufacturing method according to claim 1, wherein only thestrong alkaline salt is added.
 15. A coffee extract manufacturing methodaccording to claim 3, wherein only a combination of the strong alkalinesalt and alkaline carbonate is added.
 16. A coffee extract manufacturingmethod according to claim 4, wherein the acid is added in an amount toprevent precipitation resulting from subsequent long-term preservation.17. A coffee extract manufacturing method according to claim 16, whereinan amount of the acid is added to lower the pH by at least about 0.05.18. A coffee extract manufacturing method according to claim 17, whereinan amount of the acid is added to lower the pH by at least about 0.1.19. A coffee extract manufacturing method according to claim 18, whereinan amount of the acid is added to lower the pH by at least about 0.20.20. A coffee extract manufacturing method according to claim 4, whereinthe acid is organic acid selected from the group consisting of citricacid, malic acid, L-ascorbic acid and mixtures thereof, or inorganicacid selected from the group consisting of phosphoric acid, hydrochloricacid, and mixtures thereof, individually or in any combination of theabove acids.
 21. A coffee extract manufacturing method according toclaim 1, comprising the additional step of sealing the extract in asealed container whereby deformation of the container is prevented uponlong-term storage.
 22. A coffee extract manufacturing method accordingto claim 21, wherein, after the packaging of the extract in a sealedcontainer, flavor is preserved, no precipitation occurs and nodeformation occurs after 30 days of storage.
 23. A coffee extractmanufacturing method according to claim 22, wherein, after packaging ina sealed container, flavor is preserved, no precipitation occurs and nodeformation occurs after 60 days of storage.
 24. A coffee extractmanufacturing method according to claim 23, wherein, after packaging ina sealed container, flavor is preserved, no precipitation occurs and nodeformation occurs after 90 days of storage.
 25. A coffee extractmanufacturing method according to claim 3, wherein the strong alkalinesalt is replaced with an amount of alkaline carbonate less than about0.34% by weight of the extract.
 26. A coffee extract manufacturingmethod according to claim 25, wherein the amount of the alkalinecarbonate is less than about 0.24% by weight of the extract.
 27. Acoffee extract manufacturing method according to claim 26 wherein theamount of the alkaline carbonate is less than about 0.13% by weight ofthe extract.
 28. A coffee extract manufacturing method according toclaim 8, wherein the acid is citric acid and the alkaline carbonate issodium carbonate or sodium bicarbonate.